The invention relates to an axle assembly having multiple wheels at each end of an axle housing, and more specifically, the invention relates to a bearing arrangement for dual wheel assemblies in which one wheel is permitted to rotate relative to the other wheel.
Axle assemblies having dual wheels on either end of the axle have been used to increase the load bearing capability of heavy duty vehicles. Typically the pair of wheels on each end of the axle assembly are secured together so that they rotate together about an axis. Some heavy duty vehicles, such as lift trucks, undergo numerous turning maneuvers which wear the tires significantly. The tire wear is caused when the tires scrub, or drag, since the wheels that are secured together must travel different distances at the inside and outside of the turning radius. Tire wear and maintenance on heavy duty lift trucks due to scrub cost thousands of dollars annually per vehicle.
Dual wheel assembly designs have been proposed that permit the wheels to rotate relative to one another. Many designs have been developed which utilize a gear set between the wheels. As a result, very complex wheel bearing arrangements have been used which makes installation and removal of the wheels difficult. If only the outer wheel needs to be removed for repair, for example, both wheels and their associated bearing assemblies may need to be removed. That is, the wheel bearing arrangement for one wheel is not independent from the wheel bearing arrangement for the other wheel. Therefore, what is needed is a wheel bearing arrangement for a dual wheel assembly that is more modular which allows easy installation and removal of each wheel.
The present invention provides a dual wheel assembly for a vehicle that includes an axle assembly having an axle shaft disposed therein which defines an axis. The axle assembly has an inboard portion and an outboard portion adjacent to the inboard portion proximate to a terminal end of the axle assembly. First and second wheel hubs are supported on the outboard and the inboard portions, respectively. The first wheel hub is coupled to the axle shaft so that the first wheel hub may be driven about the axis. The second wheel hub is rotatable about the axis relative to the first wheel hub. In this manner, tire scrub is reduced since the wheel hubs may rotate at different speeds, and different directions if necessary.
A first bearing assembly is interposed between the first wheel hub and the outboard portion for supporting the first wheel hub on the outboard portion. The outboard portion has a first shoulder with the first bearing assembly abutting the first shoulder. Similarly, a second bearing assembly is interposed between the second wheel hub and the inboard portion for supporting the second wheel hub on the inboard portion, and the inboard portion has a second shoulder with the second bearing assembly abutting the second shoulder. First and second securing members are attached to the axle assembly and are adjacent to the first and the second bearing assemblies, respectively, opposite the first and the second shoulders, respectively. The first and second securing members retain the bearing assemblies against the shoulders and retain the first and the second wheel hubs on the outboard and the inboard portions, respectively. In this manner, the wheel hubs may be more easily installed and removed as units.
Accordingly, the above invention provides a wheel bearing arrangement for a dual wheel assembly that is more modular which allows easy installation and removal of each wheel.